Ball Valve Seized

[nightjar]

The ball valve on the engine sea water supply has seized! As the boat is ashore this weekend, I plan to remove the valve and fit a new one. In theory this should be straight forward but I suspect the ball valve may be seized to the through hull fitting. Can anyone who has done this job advise on what problems they encountered and the solution. My concern is that in attempting to unscrew the valve, I will potentially turn the skin fitting in the hull and damage whatever sealant was used. Any advice gratefully received.
Thanks.

 

[JerryHawkins]

Replace skin fitting too!

I had similar problems when I replaced my old gate valves with ball valves. In the end I used a power saw to cut through the skin fitting between the valve and the hull and replaced the skin fitting as well. These are cheap enough and you'll just need to get a tube if Sikaflex to bed it in. This method will probably end up being easier than fighting with stillsons or other pipe wrenches and large spanners!

Cheers,

Jerry

 

[David52]

I had a similar problem last weekend. To free up the valve on the thru hull I applied heat - using a small butane powered torch (the type that can also be used with a soldering head, bought from maplins for £5) This I found better than a full size torch as I can direct the flame better and do less "collateral" damage. In this instance the valve came free but the thru hull had been buggered about with by a previous "person or persons" so I ended up replacing it as well - this was not hard and involved buying a new one and installing it with sikka flex. On previous occasions I have been able to remove valve and replace them without disturbing the thru hull - I imagine a lot will be determined by the age and type for the installation. Also I have only done this on GRP boats. If there is a lot of obvious corrosion between the thru hull you could (if possible) apply lemon juice -which seems to eat corrosion - an if nothing else smells better than wd40 when it burns....

Hope that was of some use.

 

[silverseal]

The lemon juice trick is a good one. Citric acid attacks iron oxide and dissolves it, and unlike oxalic acid is not poisonous

 

[VicMallows]

Have also changed them between tides with no problem. Only difference is I use a polysulphide mastic (eg life caulk) since it will cure happily under water. Change the skin fitting if it is any way suspect.

Vic